ABOUT 600 friends, neighbors and artists mingled at a community barbecue May 21.

While artists, celebrities and philanthropists, including Eli Broad, Sharon Stone and Jeff Koons, attended a VIP party the day before, neighbors attended an exclusive party all their own the next day at the new Marciano Art Foundation in Windsor Square.

Several hundred area residents enjoyed an outdoor barbecue, wine, spirits and desserts on the grounds of Los Angeles’ newest private museum.

The Maurice and Paul Marciano Art Foundation’s contemporary art collection is in the former Scottish Rite Temple at 4357 Wilshire Blvd.

Most of the neighbors had never been inside the 100,000 square-foot marble-and-travertine building. Designed in 1961 by Millard Sheets, the artist who also designed the mosaics and other aspects of Home Savings and Loan buildings, it served as a cathedral to the secretive Freemasons.

Also enjoying the spring day were Carolyn, Lucy, andJamie Bennett, he a former neighbor who spent years of volunteer time addressing the former owners’ illegal uses of the property.

Architect Yantrasast renovated the light-filled space with an eye to preserving Sheets’ original design, including retaining stained glass windows and some of his stunning mosaics.

WORKS ON DISPLAY at the new museum include a photographic mural by Cindy Sherman.

The Masons’ elaborate backdrops for their costumed rituals were resurrected and are on display. Also featured are pieces from the 1,500-work collection of brothers Maurice and Paul Marciano, who made their fortune with Guess? Jeans.

The inaugural exhibit “Unpacking: The Marciano Collection,” curated by Philipp Kaiser, showcases works by artists from the 1990s to the present. It ends Dec. 24.

“Jim Shaw: The Wig Museum” is a nod to the building’s original owners, the Scottish Rite of Freemasonry, a fraternal order dating back to the 18thcentury. According to the artist, the piece is a metaphor for the wig-wearing Masonic and judiciary Anglo-Saxon power that is coming to an end. This exhibit ends Sept. 7.

Millard Sheets founded Millard Sheets Designs in 1953, and the company completed 100 murals and mosaics throughout the United States, including numerous commissions for Hancock Park-based financier, Howard Ahmanson.

The Los Angeles temple boasts a four-story mosaic on the east exterior wall of the building. It had a 2,000-seat auditorium and a large dining hall, both of which now are wide-open gallery spaces.

Sculpture groupings along the outside wall are by Albert Stewart, head of the sculpture program at Scripps College in Claremont at the time.

The Marciano Art Foundation building now features climate-controlled art storage, an outdoor sculpture garden and free on-site parking for visitors with advance reservations.